SZ Brain Structure (Bio) Flashcards
BrainStructure SZ
Enlarged ventricles
Schizophrenics have smaller brains and enlarged ventricles in comparison to people without schizophrenia
this suggest either brain tissue is being lost
or certain brain areas have failed to develop fully such as the frontal lobes, temporal loads, and hypothalamus
The neurodevelopmental hypothesis suggests that schizophrenia is due to abnormal brain development which is latient in the individual and triggered by maturation in late adollecence
Research using CAT scans reveal approximately 25% of schizophrenic patients have enlarged ventricles in the brain
Ventricles are fluid-filled cavities that supply oxygen and blood to the densely packed neurons and remove waste products
enlarged ventricles are usually caused by the death of brain tissue surrounding the ventricles and the fluid expanding to fill the space
Post mortem analysis of schizophrenic brains have shown abnormalities
– with the most consistent issue being enlarged ventricles implying a loss of brain cells
There’s also consistency with studies indicating structural issues in the subcortical temporal limbic areas such as the hippocampus and basal ganglia and the prefrontal and temporal cortexes
Brain scans reveal there are more enlarged ventricles in schizophrenic males
BrainStructure SZ
Loss of grey matter in the brain
The brain consists of Grey and white matter
– the grey matter is important as it allows communication between areas of the brain from memory, movement and emotions
– a misfire of communication could lead to auditory hallucinations for example
– in schizophrenic brains there is a reduction in volume of grey and white matter in the brain especially in the temporal and frontal lobes and in some regions there is a lot of up to 25%
• the damage starts in the paradel outer regions of the brain and spreads inwards over a five-year period
• the more brain tissue that is lost the worse the symptoms of schizophrenia
• an indication of this loss is in the enlargement of ventricles that take its place
BrainStructure SZ
Loss in PFC
The damage that occurs it is most important the schizophreno is in the PFC
Schizophrenics show low activity in this region of the brain compared to controls especially when performing cards sorting tasks
they also have reduced metabolic rates in the PFC when completing neurophysical tasks that price demands on the PFC
This may be the cause of the positive symptoms delusion, has there not using their PFC is much as others therefore logical thinking does not occur
Remember the PFC is responsible for logical thinking problem solving and amygdala inhibition
This is also why that due to reduction in activity in the PFC that organizes thoughts schizophrenex suffers from disorganized thought patterns
Often schizophrenic symptoms appear in late and lessons which is linked to when the PFC has become fully developed
therefore it may be that the damage that has occurred to the PFC does not show schizophrenic symptoms until it is fully developed
BrainStructure SZ
visual and auditory corticies
Studies show that in schizophrenic patients that suffer from hallucinations show brain activity in the visual and auditory cortices
parts of The brain that process vision sound information
in schizophrenics the brain acts in the same way whether the patient is seeing or hearing something real or hallucinating
therefore they seem real in the brain
BrainStructure SZ
loss in Basal Ganglia
In the basal ganglia that is located deep inside the brain which is involved with movement and thinking skills
schizophrenics have larger basal ganglia than normal people which may affect their movement patterns as schizophrenics often have motor dysfunctions
BrainStructure SZ
loss in the Amygdala
Schizophrenics have smaller amygdalas than normal people
which is why they show little emotion
as the amygdala is responsible for feelings
BrainStructure SZ
cause of damage
during Foetal development
Famine and virus
• it could be that a virus damage is the brain during fetal development
• in 1957 in Helsinki there was an epidemic of influenza and research is examined the rates of schizophrenia among the adults who were likely been exposed to this during pregnancy
• people exposed to virus during the second trimester had much higher rates of sz than those who exposed in another stage or not at all
cortical development is a critical stage of growth during the second trimester
This damage can also occur if there is a famine as the baby will not have enough nutrients to develop properly
BrainStructure SZ
y brain damage in pre birth but sz dev in adollecence? PFC AND DOPE
This could be due to the brain injury interacts with normal brain development
the PFC is a brain structure but doesn’t develop until late adolescence therefore an injury to this area would not be apparent until it fully developed its behaviors
dopamine activity also peaks in Adolessants which may further set the stage for the onset of schizophrenia symptoms
BrainStructure SZ
what causes loss
difficult birth
murray 1997 and Cantor Graae et al 1994
Another cause of brain damage that have been linked with later development and schizophrenia is having a difficult birth
Murray 1997 reviewed studies of birth difficulties and found that 7/8 studies found an Association between low birth weight (due too malnutrition mabye cuz famine), premature birth, prolonged labor and oxygen starvation and SZ
Cantor Graae et al 1994
Found birth difficulties has been associated with schizophrenia more frequently in those who do not have family Histories all the disease
BrainStructure SZ
TBI
Research suggests those who have enlarged ventricles also have a higher incidence to head injury too
The most popular theory of for the cause of negatives symptoms of schizophrenia is that they are the results of some sort of structural damage to the brain
While positive symptoms are unique from brain damage
For example symptoms such as catatonia, the absence of a blink reflex, speech arrest, and a poor visual Focus
are common symptoms for schizophrenia and patience that suffer from brain damage
BrainStructure SZ
evidence +
O’Callaghan et al (1991)
influenza
O’Callaghan et al (1991)
• suggested that the influence of an influence outbreak in 1957
found that amongst children who were in The 4-6 months of gestation during the Outbreak there was a high incidence of SZ
Providing evidence to support the feet tall development aspects of the cause of schizophrenia from brain structure in the neuro developmental Theory
BrainStructure SZ
evidence +
Crowe 1974
Crowe 1974
Suggested that brain structure led to negative symptoms of schizophrenia
and neurotransmitters led to the positive symptoms of schizophrenia
Allowing for both biological explanations and schizophrenia to coexist and work together providing support for both
BrainStructure SZ
evidence +
goldstein et al 1999
Found the greatest reduction in brain matter was in the Paralympic cortex ..
they scans the whole brain of schizophrenic patients and compared the size of each region to healthy controls who are matched on age, sex, SCS and ethnicity and handedness
In schizophrenic patients several areas of the cortexes were significantly smaller than in the control
The greatest differences were in the Paralympic Cortex and a related area in the middle frontal gyrus and other small differences were also noted
This therefore shows support for the theory on brain structure causing schizophrenia as it shows differing sizes of brain structures between schizophrenic patients and normal people’s
BrainStructure SZ
evidence +
Suddath et al 1990
Suddath et al 1990
Used MRIs and showed that in MZ twins when one has SZ and the other didn’t
that the SZ twins had more enlarged ventricles and reduced anterior hypothalamuses
the difference between the two were so large that the SZ twin could be identified from the brain images in 12/15 twin pairs
Supporting the brain structure explanation schizophrenia as it demonstrates that there is a difference between areas of the brain and schizophrenics and non schizophrenics
BrainStructure SZ
Reliable brain scanning methods
Brains going techniques used such as PET or MRIs are reliable as the way they are used is standardized and thus can be accurately replicated
for example PET scans involve using a radioactive tracer that enters the brain through the bloodstream and releases positrons
as the brain communicates electronically, the positron’s react with electrons and release gamma radiation
this can be detected and shown on images indicating brain activity and structure
with red areas of the image displaying high activity and blue for low activity
therefore due to being standardized method it is highly replicable and therefore reliable
